Sodium metal-based solid-state batteries hold tremendous potential for next-generation batteries owing to low-cost earth-abundant sodium resources. However, fabricating thin free-standing solid electrolytes that could cycle sodium at high current densities has been a major challenge in developing room temperature solid-state sodium batteries. By developing high conducting Zn2+ and Mg2+ dual-doped Na3Zr2SiPO12 (NASICON) solid electrolytes and fabricating a 3D porous-dense-porous architecture (with an ultrathin, 25 μm, dense separator) coated with a nanoscale ZnO layer, an extremely low anode interfacial resistance of 3.5 Ω cm2 was realized. This enabled a record high critical current density of 40 mA cm−2 at room temperature with no stack pressure and a cumulative sodium cycling capacity of 10.8 A h cm−2 was achieved. Furthermore, pouch cells were assembled as a proof-of-concept with Na3V2(PO4)3 cathodes on dense-porous bilayer electrolytes with sodium metal anodes and cycled up to 2C rates at room temperature with no applied stack pressure.

p-Type (Bi, Sb)2Te3 is the most excellent thermoelectric material near room temperature; however, the drastically declined performance makes it incapable of coping with low-grade waste heat recovery scenarios above 500 K. Herein, firstly, a great advance in thermoelectric performance is realized through reasonable composition control and microstructure design, including lithium acceptor doping to improve the electrical transport performance and subsequent Te addition to suppress the donor-like effect to further fine-tune the power factor, as well as the construction of dispersed nanopores, which leads to very low thermal conductivity. As a result, a highly competitive ZT of 1.42 at 373 K and a ZTave of 1.23 from 303 K to 523 K are achieved concurrently. Secondly, (Bi, Sb)2Te3 and its higher-temperature analogue Sb2Te3 are organized in a segmented structure by one-step sintering to broaden the temperature range. Similarly, optimized Mg3(Sb, Bi)2 materials with different high-performance temperature ranges are used to prepare the n-type segmented leg. Finally, a 2-pair module is fabricated, showing an efficiency of up to 10.5% and a power density of 0.53 W cm−2 with a temperature difference of 380 K. This work provides robust evidence for the high potential of (Bi, Sb)2Te3/Mg3(Bi, Sb)2 segmented modules for waste heat recovery.

Despite the rapid rise in the performance of a variety of perovskite optoelectronic devices with vertical charge transport, the effects of ion migration remain a common and longstanding Achilles’ heel limiting the long-term operational stability of lead halide perovskite devices. However, there is still limited understanding of the impact of tin (Sn) substitution on the ion dynamics of lead (Pb) halide perovskites. Here, we employ scan-rate-dependent current–voltage measurements on Pb and mixed Pb–Sn perovskite solar cells to show that short circuit current losses at lower scan rates, which can be traced to the presence of mobile ions, are present in both kinds of perovskites. To understand the kinetics of ion migration, we carry out scan-rate-dependent hysteresis analyses and temperature-dependent impedance spectroscopy measurements, which demonstrate suppressed ion migration in Pb–Sn devices compared to their Pb-only analogues. By linking these experimental observations to first-principles calculations on mixed Pb–Sn perovskites, we reveal the key role played by Sn vacancies in increasing the iodide ion migration barrier due to local structural distortions. These results highlight the beneficial effect of Sn substitution in mitigating undesirable ion migration in halide perovskites, with potential implications for future device development.

Furfuryl alcohol (FA), formate (FM), and H2 are important chemicals used in various chemical manufacturing industries. One promising approach for the simultaneous production of these chemicals is coupling cathodic furfuryl electrochemical hydrogenation (FEH) with anodic formaldehyde oxidation reaction (FOR) in an electrolyzer using bifunctional electrocatalysts. Here, bifunctional catalysts (CuxAgy/CF) are designed to achieve faradaic efficiency of 95.6 and 100.0% for FA and FM coproduction, respectively. This innovative technology not only achieves more valuable anodic products than oxygen but also simultaneously produces H2 at both anode and cathode at ultra-low voltage. Through density function theory (DFT) calculations and in situ spectroscopy analysis, it is demonstrated that the CuxAgy/CF electrocatalysts optimize the adsorption of intermediates ((C4H3O)CH2O* and H2C(OH)O*) and greatly reduce the energy barriers of rate-determining steps. The Cu3Ag7/CF(+)||Cu7Ag3/CF(−) electrolyzer reaches a current density of 500 mA cm−2 with a cell voltage of only 0.50 V, providing an effective method to simultaneously generate valuable chemicals (FA, FM, and H2).

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Aqueous zinc-ion batteries (ZIBs) distinguish themselves among the numerous viable alternatives to lithium-ion batteries on account of their potential advantages, which encompass enhanced safety, cost-effectiveness, and eco-friendliness. However, the metal zinc (Zn) that makes ZIBs competitive is now being plagued by dendrite growth and spontaneous side reactions (hydrogen evolution reaction and water-induced corrosion). These unavoidable parasitic reactions degrade the output energy/power density and shorten the actual lifespan of the Zn anode, rendering it infeasible for ZIBs to access the practical energy storage system. Herein, we systematically summarize the host-design strategies for the Zn anode regarding substrate (accommodation of Zn deposits) and interface (protection of Zn anode) fabrications. In addition, for the purpose of developing a Zn anode that is chemically and electrochemically stable, we thoroughly elucidate the internal mechanisms of the regulation strategies while offering guidance for the rational design of Zn anodes. This review may suggest a prospective guideline for developing high-performance Zn anodes for use in sustainable ZIBs.

Extracting, processing, and delivering energy requires energy itself, which reduces the net energy available to society and yields considerable socioeconomic implications. Yet, most mitigation pathways and transition models overlook net energy feedbacks, specifically related to the decline in the quality of fossil fuel deposits, as well as energy requirements of the energy transition. Here, we summarize our position across 8 key points that converge to form a prevailing understanding regarding EROI (Energy Return on Investment), identify areas of investigation for the Net Energy Analysis community, discuss the consequences of net energy in the context of the energy transition, and underline the issues of disregarding it. Particularly, we argue that reductions in net energy can hinder the transition if demand-side measures are not implemented and adopted to limit energy consumption. We also point out the risks posed for the energy transition in the Global South, which, while being the least responsible for climate change, may be amongst the most impacted by both the climate crisis and net energy contraction. Last, we present practical avenues to consider net energy in mitigation pathways and Integrated Assessment Models (IAMs), emphasizing the necessity of fostering collaborative efforts among our different research communities.

Because of the high abundance, cost-effectiveness and low redox potential of Na, rechargeable Na metal batteries (NMBs) are considered an ideal alternative and complementary to state-of-the-art lithium-ion batteries. Despite numerous research efforts that have been made to accelerate the development of the NMBs utilizing both liquid- and solid-state electrolytes, issues such as Na dendrite formation, undesirable side reactions, and infinite volume changes remain to be addressed. This review paper presents a thorough examination of the progress and accomplishments of liquid-based and solid-state NMBs. It encompasses a comprehensive analysis of fundamental studies and practical applications, an extensive comparison between Li and Na metal anodes, along with an in-depth discussion of the fundamentals of Na dendrite formation in both liquid- and solid-state electrolytes. Furthermore, we summarize various promising approaches for addressing the associated issues and challenges. Through our review, we aim to accelerate the progress in comprehending and utilizing Na metal anodes for practical NMB systems.

Alkaline-based aqueous batteries have attracted intensive research interests due to their high voltage, low cost, and high safety. However, metal anodes in alkaline electrolytes usually possess poor stability and severe side reactions. Organics are potential alternatives to address these problems, but they are typically not negative enough as anodes. Herein, a group of organic phenazine derivatives including phenazine (PZ), 2-hydroxyphenazine (PZ-OH), and 1,2-dihydroxyphenazine (PZ-2OH) are developed as anode materials for alkaline-based batteries. It is revealed that introducing hydroxyl groups can lower the redox potential by 0.4 V, and fast ion transport channels formed by intramolecular hydrogen bonds can remarkably improve redox kinetics. The optimized PZ-2OH‖Ni (OH)2 batteries deliver a high capacity of 208 mA h g−1anode, a high energy density of 247 W h kg−1anode, and ultra-stable cyclability up to 9000 cycles with a low-capacity decay rate (approximately 0.075‰ capacity decay rate per cycle). Meanwhile, we also demonstrate an alkaline PZ-2OH‖air cell, further proving the applicability of PZ-2OH under alkaline conditions. This work not only explores the effect of hydroxyl substituents on the electrochemical potential and reaction kinetics but also opens up the door to stable anodes for alkaline-based batteries.

Charge separation is a crucial process that is closely related to the field of information and energy applications such as optoelectronics, photovoltaics, and artificial photosynthesis. The S-scheme electron transfer is widely used to regulate carrier separation due to its unique superiority. However, as our understanding of this field continues to evolve, there remain many controversial and ambiguous issues that are not well addressed. Focusing on the S-scheme electron transfer, this perspective delves into the reasons behind the confusion between the mechanisms of type-II and S-scheme transfer and clearly affords the theoretical criteria for the establishment of type-II transfer and S-scheme transfer. Considering the Fermi level alignment in a heterojunction is only applicable to the ideal situation, but not to the actual situation. The theory of Fermi level bending is further elaborated. To answer the question of whether the S-scheme driving force can be sustained, the phenomenon of Fermi level pinning is discussed intensively. Finally, the current problems and future development directions of S-scheme electron transfer are summarized and prospected.

Static metal–semiconductor contacts are classified into Ohmic contacts and Schottky contacts. As for dynamic metal–semiconductor contacts, the in-depth mechanism remains to be studied. We here define a “triboelectric junction” model for analyzing dynamic metal–semiconductor contacts, where a space charge region induced by the triboelectric effect dominates the electron–hole separation process. Through theoretical analysis and experiments, we conclude that the triboelectric junction influences the electric output in two aspects: (1) the junction direction determines the output polarity; (2) the junction strength determines the output magnitude. Both the junction direction and junction strength are closely related to the electron-affinity difference between the contact metal and semiconductor.

High-voltage rechargeable magnesium batteries (RMBs) are potential alternatives to lithium-ion batteries owing to the low cost and high abundance of magnesium. However, the parasitic reactions of the latter with many electrolytes greatly hinders the stability and kinetics of Mg plating/stripping. Here we report a new and easily accessible solvent-designed electrolyte, which effectively solves the difficulty of ion pair dissociation and facilitates fast nanoscale Mg nucleation/growth using simple Mg(TFSI)2 as the salt, enabling a facile interfacial charge transfer process. Dendrite-free Mg plating/stripping is maintained for over 7000 hours (∼10 months) at a practical areal capacity of 2 mA h cm−2. The high-voltage stability of these electrolytes is demonstrated by benchmarking with polyaniline||Mg full cells with an operating voltage up to 3.5 V that exhibit stable cycling at a 2C rate with 99% coulombic efficiency after 400 cycles. This work opens up new frontiers in coupling low-cost electrolytes with next-generation high-voltage cathode materials for fast-charging RMBs with long life and high energy densities.

Forecasting the real-world stability of perovskite solar cells (PSCs) using indoor accelerated tests is a significant challenge on the way to commercialising this highly anticipated PV technology. The lack of outdoor data and considerable magnitude of meta-stability effects (or reversible changes) in PSCs’ performance over the day–night cycle makes it particularly challenging to correlate results of the commonly utilised light-soaking ageing test with outdoor experiments. Here we show the variety of short-term and long-term ageing behaviours by testing PSCs of various architectures under constant and intermitted light indoors and exposing them to natural conditions outdoors. We demonstrate that it is impossible to predict the results of a light cycling test from a continuous light test without prior knowledge of the ageing patterns for a particular device architecture. Cycling the light does not necessarily lead to an increased lifetime as expected due to dark time recovery. Instead, it sometimes reveals a different degradation behaviour resulting in a drastic lifetime reduction. The presence of various degradation patterns for different PSCs implies that an accelerated ageing with constant light experiment is no “worst-case scenario” and thus cannot replace the light cycling test nor can it reproduce the real-world scenarios. Furthermore, we show unique sets of weeks-to-years-long outdoor series on different PSCs highlighting the monumental importance of accounting for the meta-stability effects when analysing PSC outdoor data as opposed to simply following evaluation routines developed for silicon-based devices. In particular, meta-stability complicates the decoupling of the effects of environmental conditions from the cell's ageing behaviour and can result in large artefacts. A varying degree of saturation of reversible processes also results in unusual strong seasonality documented for PSCs, with summer representing favourable conditions for some PSCs’ energy generation compared to winter, despite higher temperatures. For the first time, the decisive impact of meta-stable processes on the outdoor performance and stability of perovskite solar cells is demonstrated, with data from over two years in the field, which is the longest outdoor exposure of PSCs reported so far to the best of our knowledge. The correlation between the outdoor results and those from the light cycled experiments is evident.

Oxygen-redox-active (ORA) layered oxide cathodes for sodium-ion batteries have received considerable attention due to their ultrahigh capacity. However, the voltage decay during electrochemical cycling in such materials is still elusive and unsolved, which seriously limits their practical implementation. Herein, we unveil the intrinsic origin of voltage decay in sodium-based ORA cathodes by coupling spatially local electron energy loss spectroscopy with bulk-sensitive X-ray absorption spectroscopy. It is demonstrated that the steric heterogeneity of Mn redox derived from the surface formation of oxygen vacancies is responsible for the voltage deterioration upon cycling. Moreover, we propose an ORA cathode (Na0.8Li0.24Al0.03Mn0.73O2) with negligible voltage decay. Its oxygen redox reversibility is significantly strengthened because the strong Al–O bonds weaken the covalency of Mn–O bonds to promote the electron localization on oxygen. These findings suggest a new insight into the electronic structure design of high-energy-density cathode materials for advanced rechargeable batteries.

Reversibility of oxygen anionic redox (OAR) in 3d transition-metal layered oxides holds the key to its practical utilization in sustainable batteries. However, the influence of cationic superstructure ordering on the reversibility of OAR during long-term battery operation remains unclarified. Herein we explore an inconsistency between the superstructure stability and long-term cyclability of OAR by comparing two contrasting systems, i.e., ribbon superstructured P2- and P3-Na0.6Li0.2Mn0.8O2. The “less Li and more Na” feature of the O-type domain formed in desodiated P3-Na0.6Li0.2Mn0.8O2 provides the driving force for the reconstruction of the ribbon superstructure, while the “more Li and less Na” feature formed in desodiated P2-Na0.6Li0.2Mn0.8O2 does not, thereby bringing about a better stability of the superstructure and a decent reversibility of local Mn–O coordination for P3-Na0.6Li0.2Mn0.8O2. More importantly, we reveal that the progressive loss of the ribbon superstructure and the accompanying sluggish local structural rearrangements occurring in P3-Na0.6Li0.2Mn0.8O2 result in a worse cyclability of OAR relative to P2-Na0.6Li0.2Mn0.8O2. It is thus reasonable to conclude that it is the reversible out-of-plane displacement of Li+ that intrinsically governs the cyclability of OAR rather than the stability of the superstructure. These findings represent a conceptual breakthrough towards the impact of the superstructure on the behavior of OAR.

Single-atom catalysts with M–N4 configurations have been highly investigated due to their great potential in oxygen electrocatalysis. However, their practical applications in Zn–air batteries are still impeded by the unsatisfied activity and durability. Herein, we develop a dual-metal single-atomic NiFe–N–C catalyst containing Fe nanoclusters by simply pyrolyzing metal phthalocyanine and N-doped carbon precursors. A series of in situ spectroscopic characterizations and density functional theory calculations provide compelling evidence of the co-existence and electronic synergy of Ni–N4 and Fe–N4 coordination structures as well as adjacent coupled Fe nanoclusters, which regulate the electronic structure of catalytic active sites and optimize their adsorption/desorption of oxygenated intermediates, accelerating the reaction kinetics and reducing the energy barrier of the oxygen electrocatalysis. As a result, NiFe–N–C exhibits competitive oxygen evolution/reduction reaction (OER/ORR) activity and durability with an ultrasmall ΔE of 0.68 V and a negligible decay of E1/2 and Ej10 after 50 000 and 90 000 potential cycles, respectively. In addition, Zn–air batteries based on a NiFe–N–C electrocatalyst with a high power density, high specific discharge capacity and ultralong lifespans are realized. This work provides an effective strategy for synergistic electronic modulation of atomically dispersed metal sites, paving a new way for designing advanced bifunctional oxygen electrocatalysts and beyond.

Zinc-based flow batteries are receiving huge attention due to their attractive features of high energy density and low cost. Nevertheless, their reliability is normally limited by dendritic zinc in the anode, which is influenced by the enormous difference in the transfer rate of zinc species in bulk solution and their electrochemical reaction rate at the anode. Here we engineer an artificial bridge between the anode and the anolyte enabled by organic ligands to realize fast transfer of zinc species from bulk solution to the interfacial region of the anode for zinc-based flow batteries. The ligands serve as the bridge in constructing a directional three-dimensional transport channel for zinc species first by coordination with zinc species and then adsorption on the surface of the anode, which enables a highly uniform and dense zinc morphology. Remarkably, an alkaline zinc–iron flow battery cell stacked with the organic ligand in the anolyte achieves stable cycling for ∼700 hours at 40 mA cm−2 with an average coulombic efficiency of 98.04% and an energy efficiency of 88.53%, respectively. This work presents a promising solution to address the issue of zinc dendrites and offers a path for developing highly reliable electrolytes for low-cost and sustainable zinc-based flow batteries.

Moisture-based adsorption thermal batteries (ATBs) have the potential to alleviate the temporal and geographic mismatch between heat producers and heat consumers, but realizing practical applications is still challenging, in spite of the huge developments in novel materials and system design. Here, a proof-of-concept solar Trombe-wall (T-wall)-based ATB prototype with honeycomb-design, scalable, and low-cost CaCl2-based fiber brick with ink (ICFB) sorbents is reported for the first time. The ICFB achieves an outstanding thermal storage capacity of 172.8 kW h m−3 and good stability in heat charging–discharging cycles. Importantly, the idea of the solar chimney effect in passive building heating is introduced into the system structural design to pursue optimal thermal output and energy saving. Together with the rational operating strategy, the T-wall-based ATB prototype shows exceptional thermal performance, achieving a heat discharging power density of 1.97 kW m−3, a discharging efficiency of 64.8%, an energy utilization coefficient of 0.87 kW ht kW hc−1, and an energy consumption coefficient of 1.32 kW he kW hts−1 reduced by 54.2% in comparison with 100%-electricity use, demonstrating its adaptability and possibility of realizing day and night heating in low-carbon scenarios.